Toffoli gate based on a three-body fine-structure-state-changing Forster resonance in Rydberg atoms

We have developed an improved scheme of a three-qubit Toffoli gate based on a fine-structure-state-changing three-body Stark-tuned Rydberg interaction. This scheme is a substantial improvement of our previous proposal [I. I. Beterov et al., Phys. Rev. A 98, 042704 (2018)]. Due to the use of a different type of three-body Forster resonance we substantially simplified the scheme of laser excitation and phase dynamics of collective three-body states. This type of Forster resonance exists only in systems with more than two atoms, while the two-body resonance is absent. We reduced the sensitivity of the gate fidelity to fluctuations of external electric field and eliminated the necessity to use external magnetic field for fine-tuning of the resonant electric-field value, compared to the previous scheme of Toffoli gate based on Rydberg atoms. A gate fidelity of > 99% was demonstrated in the calculations.